Equal-length exhaust discussion: new S55 sounds

[Jamongkad]

Originally Posted by bsm.m4

No sound clips yet, getting a bunch of other work done too but here's a sneak peak at the AA EL midpipe install with a new Dinan axle back. Don't worry, I'll make tons of videos!

Now this is a setup I want to hear!

[1000hp]

Anybody else get a mild drone at 3k RPM under load?

[rborane]

Originally Posted by 1000hp

Anybody else get a mild drone at 3k RPM under load?

Yes. I have the non-resonated with factory downpipes, and with valves wide set to always open on BM3, the drone is unbearable. Setting the valves to OEM settings fixed the drone entirely, and makes it much more enjoyable to drive. Seems that is the consensus when running valves wide open, as it is essentially a straight pipe

[RugbyBro]

Originally Posted by 1000hp

Anybody else get a mild drone at 3k RPM under load?

Yup, as rborane said above, it's effectively a straight pipe with valves open. Take a look at bsm.m4's pic above - although it's a Dinan axel-back, the OE exhaust routing is philosophically the same (pic below as well). Closed routes though the muffler, open routes directly out with only some gas coming through the muffler. Stock valve control closes the valves even in sport/sport+ under 3k + above second gear to avoid drone. If you do a third gear run from 1.5k you can audibly hear when the valve opens at 3k.

[1000hp]

Originally Posted by RugbyBro

Yup, as rborane said above, it's effectively a straight pipe with valves open. Take a look at bsm.m4's pic above - although it's a Dinan axel-back, the OE exhaust routing is philosophically the same (pic below as well). Closed routes though the muffler, open routes directly out with only some gas coming through the muffler. Stock valve control closes the valves even in sport/sport+ under 3k + above second gear to avoid drone. If you do a third gear run from 1.5k you can audibly hear when the valve opens at 3k.

So is there an axle back that doesn't drone, but flows well and sounds good with this midpipe??

I had the single midpipe prior to this, and there was ZERO drone at any RPM. It didn't sound as nice as this one, but god I can't stand drone. It was kind of a kick in the balls to install this expensive pipe that everyone raves about, and hear it start moo'ing at 3,000RPM.

[RugbyBro]

Originally Posted by 1000hp

So is there an axle back that doesn't drone, but flows well and sounds good with this midpipe??

I had the single midpipe prior to this, and there was ZERO drone at any RPM. It didn't sound as nice as this ome, but god I can't stand drone. It was kind of a kick in the balls to install this expensive pipe that everyone raves about, and here it start moo'ing at 3,000RPM.

I find that with OE valve control there is no drone under 3k rpm - there is only a small window of roughly 500rpm of audible drone from 3-3.5k to my ears. After 3.5k it opens up and starts screaming. It hasn't been an issue for me because I don't live in that 500rpm range, but other people's driving style may be different. For my driving style, I'm either granny mode or rev mode - If I am going to hit 3k then chances are I'm actually going to shift somewhere above 4.

Possible options could be to have some resonators installed, or to have a muffler with very little insulation so you can run with the valves closed and still get decent volume (maybe something like an MPE or equivalent design).

I guess as a question, are you stock everything else besides the mid pipe?

[ntg44]

Originally Posted by 1000hp

So is there an axle back that doesn't drone, but flows well and sounds good with this midpipe??

I had the single midpipe prior to this, and there was ZERO drone at any RPM. It didn't sound as nice as this one, but god I can't stand drone. It was kind of a kick in the balls to install this expensive pipe that everyone raves about, and hear it start moo'ing at 3,000RPM.

Are you getting drone with valves closed?

[1000hp]

Originally Posted by RugbyBro

I find that with OE valve control there is no drone under 3k rpm - there is only a small window of roughly 500rpm of audible drone from 3-3.5k to my ears. After 3.5k it opens up and starts screaming. It hasn't been an issue for me because I don't live in that 500rpm range, but other people's driving style may be different. For my driving style, I'm either granny mode or rev mode - If I am going to hit 3k then chances are I'm actually going to shift somewhere above 4.

Possible options could be to have some resonators installed, or to have a muffler with very little insulation so you can run with the valves closed and still get decent volume (maybe something like an MPE or equivalent design).

I guess as a question, are you stock everything else besides the mid pipe?

Yes, stock everything except for the midpipe.
This is the resonated midpipe, too. I wonder if the drone is more or less pronounced with the non-resonated version. I've had other exhausts on other cars where deleting the factory resonator completely killed the factory drone, like the single midpipe did for this car (mild drone in 6th gear on the interstate).

[1000hp]

Originally Posted by ntg44

Are you getting drone with valves closed?

No.
I'm thinking that an axle back that sounds good without becoming a straight pipe might be my best bet.

[ntg44]

Originally Posted by 1000hp

No.
I'm thinking that an axle back that sounds good without becoming a straight pipe might be my best bet.

Well I think your only option would be AA mad max muffler. The reason the stock muffler drones is because it was designed for stock tone frequencies, and EL messes with those pitches pretty significantly. With that said, if you don’t have drone with valves closed, I’d say the muffler is doing its job. The mad max doesn’t have straight pipes in its open valve state, so it’s worth a look. The large helmholtz chambers may help with the drone.

[1000hp]

Originally Posted by ntg44

Well I think your only option would be AA mad max muffler. The reason the stock muffler drones is because it was designed for stock tone frequencies, and EL messes with those pitches pretty significantly. With that said, if you don’t have drone with valves closed, I’d say the muffler is doing its job. The mad max doesn’t have straight pipes in its open valve state, so it’s worth a look. The large helmholtz chambers may help with the drone.

It looks like the Mad Max goes to straight dumps with the valves open 🤔
But yeah I would imagine that 3rd can does a good job with the resonance. I would probably opt for the original 3-can without the cutouts for $$$ less. But then I would hate for it to be too quiet, and not have the valves at all to open it up for sound.

[rborane]

Originally Posted by 1000hp

Yes, stock everything except for the midpipe.
This is the resonated midpipe, too. I wonder if the drone is more or less pronounced with the non-resonated version. I've had other exhausts on other cars where deleting the factory resonator completely killed the factory drone, like the single midpipe did for this car (mild drone in 6th gear on the interstate).

If you are on stock downpipes, I would run the non-resonated pipes and set valves to OEM. I think you will like it. It almost reminds me of how GT3's sound to where it is a very distinct sound when you hear the valves open fully lol. Running OEM valve settings you will get rid of most, if not all of the drone too like @rugbybro mentioned

[ntg44]

Originally Posted by 1000hp

It looks like the Mad Max goes to straight dumps with the valves open ��
But yeah I would imagine that 3rd can does a good job with the resonance. I would probably opt for the original 3-can without the cutouts for $$$ less. But then I would hate for it to be too quiet, and not have the valves at all to open it up for sound.

Yes but they are not in the direct path of the exhaust flow. They are off to the side so the effect is less than other rear sections with dedicated straight pipes that reroute to the muffler when valves are closed. There is a difference, and not all of the sound goes through the open section. In my opinion this is by far the safest option for drone cancellation.

Another benefit after looking at it again is that it hits the helmholtz resonator before the open pipe. This is a big benefit versus other mufflers.

[JamesGames]

I've ran the Dinan / EL setup since november and love it so far - besides the cold start with valves open. It basically screams on cold start and is an "F you" to the neighborhood upon cold start especially because it has some rasp. All is good when warm though - smooth buttery straight 6 noises.

I will probably get a valve controller.

[1000hp]

Originally Posted by rborane

If you are on stock downpipes, I would run the non-resonated pipes and set valves to OEM. I think you will like it. It almost reminds me of how GT3's sound to where it is a very distinct sound when you hear the valves open fully lol. Running OEM valve settings you will get rid of most, if not all of the drone too like @rugbybro mentioned

👍🏼I'll try that

[FAM3LYCAR]

I posted a while back about some small leaks at the clamp locations right after install of my non-res EL mid pipe but after a few rounds of adjustments and about 500 miles on it now I’m happy to say all is good!

I’m all stock other than the midpipe and have no drone whatsoever at any RPM range. I was on the highway for 2 hours recently and couldn’t make it drone if I wanted to, in any setting.

Cold starts are awful like everyone says but I expected that and gave my neighbors advance notice but they still hate me.

[1000hp]

Originally Posted by ntg44

Yes but they are not in the direct path of the exhaust flow. They are off to the side so the effect is less than other rear sections with dedicated straight pipes that reroute to the muffler when valves are closed. There is a difference, and not all of the sound goes through the open section. In my opinion this is by far the safest option for drone cancellation.

Another benefit after looking at it again is that it hits the helmholtz resonator before the open pipe. This is a big benefit versus other mufflers.

Interesting. I may give that a try. It would be easier to experiment if these parts weren't $3,000+.
I promised myself I wouldn't go down the exhaust rabbit hole like I did with my e36 M3 (literally ten different mufflers and six different midpipes in various combinations) but I'm not off to a good start here lol.

[1000hp]

Originally Posted by JamesGames

I've ran the Dinan / EL setup since november and love it so far - besides the cold start with valves open. It basically screams on cold start and is an "F you" to the neighborhood upon cold start especially because it has some rasp. All is good when warm though - smooth buttery straight 6 noises.

I will probably get a valve controller.

The valve controller is worth every penny. I have mine programmed to the garage door opener buttons on the mirror. Works well.

[1000hp]

Originally Posted by FAM3LYCAR

I posted a while back about some small leaks at the clamp locations right after install of my non-res EL mid pipe but after a few rounds of adjustments and about 500 miles on it now I’m happy to say all is good!

I’m all stock other than the midpipe and have no drone whatsoever at any RPM range. I was on the highway for 2 hours recently and couldn’t make it drone if I wanted to, in any setting.

Cold starts are awful like everyone says but I expected that and gave my neighbors advance notice but they still hate me.

This thing is 100% air tight. I'm fanatical about that.
Gonna try the non-res rear pipes and will report back. My neighbors are cool. We'll see how cool they stay...

[1000hp]

Quick update: I put the non-res rear pipes on it tonight. Not much change. I like the resonators better.
Time to sell my organs for a muffler.

[mike@x-ph.com]

Originally Posted by 1000hp

Quick update: I put the non-res rear pipes on it tonight. Not much change. I like the resonators better.
Time to sell my organs for a muffler.

[1000hp]

Originally Posted by mike@x-ph.com

lol Standing by for coupon codes 😬